Evaluation of QMS Everolimus Assay Using Hitachi 917 Analyzer: Comparison With Liquid Chromatography/Mass Spectrometry

Abstract

Everolimus is an immunosuppressant requiring routine monitoring in whole blood. We evaluated the analytical performance of a new immunoassay for everolimus, Quantitative Microsphere System (QMS) everolimus (Thermo Fisher Scientific), which is CE marked and currently under review by Food and Drug Administration of the United States by comparing results with values obtained by using liquid chromatography/mass spectrometry. The total coefficient of variations (CVs) were 8.3% for low control (mean: 3.8 ng/mL), 6.1% for the medium control (mean: 8.0 ng/mL), and 7.5% for the high control (mean: 14.4 ng/mL) (n = 80 for each control, run over 20 nonconsecutive days). The respective total CVs for patients' pool were 13.3% (mean: 4.0 ng/mL), 7.5% (mean: 8.2 ng/mL), and 8.7% (mean: 11.7 ng/mL) (n = 80 for each patient pool). The assay was linear from a whole-blood everolimus level between 1.5 and 20 ng/mL, and the limit of quantitation was 1.3 ng/mL. Comparison was carried out using 90 renal transplant patient samples, and we observed the following Passing and Bablok linear regression plot: y = 1.11, slope = -0.005 (R = 0.92). This assay was not affected by commonly used 70 drugs, but sirolimus, a drug structurally similar to everolimus, showed 46% cross-reactivity. We conclude that QMS everolimus immunoassay has adequate sensitivity and specificity for the determination of whole-blood everolimus and can be used for routine therapeutic drug monitoring.

Therapeutic drug monitoring of immunosuppressants by liquid chromatography–mass spectrometry

“…The Quantitative Microsphere System (QMS) by Thermo Fisher, for the analysis of everolimus, has been recently cleared by the Food and Drug Administration (FDA). Validation has been reported on the Hitachi 917 [27], OrthoVitros 5,1 [28], and Indiko [29]. An 11% average bias was reported for the Hitachi 917 QMS assay and 3% underestimation with the Indiko QMS assay.…”

Oral intake of curcumin markedly activated CYP 3A4: in vivo and ex-vivo studies

“…The blood EVL concentration was measured by a QMS® Everolimus Immunoassay kit supplied by Thermo Fisher Scientific (Fremont, CA, USA), which had been reported comparable with LC-MS method31. The assay was calibrated for concentration range from 1.5 to 20 ng/mL.…”

“…A portion of serum was characterized prior to and after hydrolysis with sulfatase/glucuronidase following a previous method using LC-MS/MS with some modifications31. Briefly, 100 μL serum sample was mixed with 50 μL pH 5 acetate buffer or sulfatase (type H-1 from Helix pomatia , containing 1000 units/mL of sulfatase and 39,861 units/ml of β-glucuronidase), 50 μL ascorbic acid (200 mg/mL) and incubated at 37 °C for 30 min.…”

Long-Term Cross-Validation of Everolimus Therapeutic Drug Monitoring Assays

“…This can be explained by the fact that, as aforementioned, the QMS calibrators are adjusted based on the LC-MS/MS results of a training set of trough samples from adult renal transplant patients 7 , thus compensating for the average positive bias caused by the metabolites. Nevertheless, a previous study had observed a positive bias of 11% of the QMS assay compared to LC-MS/MS 15 . Such a positive bias was confirmed by two more recent studies 16,17 .…”